By David Hawke -- Aphids on your garden plants can be a real drag, as aphids obtain their food by piercing the stem of a plant to get the sap. Most guide books and web sites offer oodles of ways to kill them, however, as with any species of wildlife, the closer you look, the more interesting things get!
A few years ago, grandson Toby and I discovered a tree branch covered in white fluff; a closer look revealed the fluff was a colony of woolly alder aphids, each individual being covered in longish white waxy strands. On the forest floor directly beneath this mass of critters was a greasy looking stain that lay thickly upon the old fallen leaves.
We did a bit of research on these woodland fairies and found that one of their characteristics, which grandson Toby found hilarious at the time, is that they poop sugar. Plant sap is mostly sugar, but what the aphids need for nutrition is the other stuff in sap, so much of the sugar is considered waste and is excreted. "They poop sugar! Whee-hee-hee, ha-ha-ha! Sugar poops!" I guess at age eight any reference to poop is considered some of the best comedy ever to be heard.
Of course, when a plant gets covered in sticky sugar poop, it's bound to attract attention. Considering that aphids are slow, plump and soft-bodied, their list of predators is long, although comprised mainly of other insects. Ants are well known to forage for this sugar; however, they will also guard the aphids from becoming prey to other insects. Sometimes these ants will even massage the aphids to get more sugar poops to collect. Now that I think about it, the relationship between ants and aphids is much like that between humans and honey bees.
Aphids have a pair of tailpipes, called comicles, which aid in their defence, should they find themselves under attack and ant-less. A waxy substance can be released which gums up the mouth parts of the attacking creature, a ploy that could be woven into a Marvel super-hero movie, I'm sure.
But say that there is an attack by a ladybird beetle that thwarts the gummed-up mouthparts ploy, and continues on its rampage. The surviving aphids quickly disperse, some dropping to the ground, others simply walking away. "Don't make eye contact, just keep walking, and everything will turn out just fine." While doing this urban survival tactic, the aphids also emit a pheromone that others in the colony can sense and word spreads between the aphids faster than Twitter that trouble has come to town.
However, just like a well-trained kick-boxer, an aphid can and will fight back if pressed too far. They use their hind feet to pummel the marauders until they back off, or go find another less aggressive aphid to eat. A couple of aphid species also have spines that add to the challenge of them becoming fast food; but some predatory insects don't mind taking their time chewing their food in a responsible manner.
Now, if you have done battle with aphids yourself (not for food, but for the protection of your precious plants) you may wonder how and why there can be so many of them, appearing so fast? Aphids have a rather unique manner of reproduction, as they eliminate the pesky "find a compatible mate" step and just start dropping babies. A male is required, but only once and by only one queen. All of her offspring come pre-pregnant, so babies are developing inside babies inside babies. That is so weird! Like those Ukrainian wooden eggs that has one nested inside another, so too are aphids.
A scientist who dabbles in math has calculated that in one season, without any predation occurring, a single queen can be responsible for 600 billion descendants. In one season! Her birthday card list must be a bear to manage.
Time to wrap this up and have a snack. "Hey, Toby, wanna have a bee barf sandwich?" Silence. Questioning look. "You know, how some people think that honey is just bee vomit?*" Big eyes. Okay, can somebody explain to this Grandpa why "poop" is hilarious, and "vomit" is not? Man, it's tough to understand kids these days.
(*Honey is NOT bee barf, it comes from a storage sac within the honeybee, beside the stomach. So there. Relax.)
Dave’s Notebook: I hope that you can escape, even for a while, the turmoil that has enveloped the world. Take a break from elections, COVID, fire, floods and the general mayhem of society and go find a tree to hug -- literally, figuratively and metaphorically. Our salvation lies within Nature.
© 2021 David J. Hawke